Additive manufacturing, or three-dimensional printing, is an increasingly employed method for fabricating commercial and industrial products. In contrast to traditional machining techniques in which resource material may be cut or drilled away from a larger input stock material and discarded, additive manufacturing requires little, if any, disposal of the resource materials that are used to fabricate the desired part. The additive manufacturing process involves the successive depositing of layers of the part on a surface according to a digital three-dimensional representation of the part stored on a computer. More specifically, the digital representation of the part is sliced into multiple horizontal cross-sections and the computer directs a connected machine to deposit layers of the desired component on the surface according to the dimensions of the sliced digital cross-sections.
In order to improve the strength and structural resilience of manufactured parts, fibers having a strength that exceeds the strength of the material(s) forming the part may be incorporated into the body of the part. By virtue of the incorporated fibers, such fiber-reinforced parts may have improved mechanical properties such as increased impact strength, tensile strength, and modulus of rigidity. The incorporated fibers may be continuous fibers, or long fibers, that may have a fiber length to diameter ratio of between about 200 to about 500 or more. The continuous fibers may include one or more types of woven or non-woven fibers such as rayon cords, fiber glass, metallic wires, aramid fibers, and several others. However, as of yet, technologies allowing the incorporation of structurally reinforcing continuous fibers into parts by additive manufacturing methods are still wanting.
Current methods for fabricating continuous fiber-reinforced parts may involve impregnating layers of the continuous fiber with a resin adhesive to form “prepregs” which may then be layered in a mold by a manual and arduous process until the desired part thickness is achieved. The layered prepregs may then be cured and solidified by subjection to heat and pressure. One additive manufacturing technique, as described in U.S. Patent Application Number 2012/0258250, forms a polymeric three-dimensional part and a polymer support structure that at least partially encapsulates the three-dimensional part. Layering of the three-dimensional part and its surrounding support structure occur simultaneously on a surface by additive manufacturing. However, the support structure does not include a continuous fiber and the support structure does not integrate into the body of the three-dimensional part. Certainly, the development of additive manufacturing technologies that allow the integration of structurally reinforcing fibers into the material(s) forming the body of the part may provide parts with superior mechanical properties, while leveraging the efficiency and ease of production of additive manufacturing processes.
Clearly, a system is needed to allow the incorporation of structurally reinforcing continuous fibers into parts by additive manufacturing.